Syllabus

Extended Syllabus PDF

Last Week

Week 4 - Presentation LINK

• assigment <-
• comments #

Book

(Pg. 22-27)

R Files

R Script

R Notebook

R Notebook

R Notebook - HTML

R Notebook - PDF

R Notebook - WORD

R Markdown

BONUS - R Shiny

BONUS - R Shiny

LINK

BONUS - R HTML

LINK

Your R Notebook

GitHub

LINK

GitHub

GitHub

GitHub

R Language

• Scientific Calculator

• Class

• Vectors

• Matrices

• Arrays

Scientific Calculator

?Arithmetic or help(“Arithmetic”)

• ^ (exponentiation)
• sqrt (the square root)
• log (logarithm)
• exp (exponential)
• D (derivative)
• integrate (integration)
• sin (sinus)
• cos (cosinus)
• sum (sum)
• mean (mean)

example(integer) , demo(graphics)

Scientific Calculator

R> 2+3
[1] 5
R> 14/6
[1] 2.333333
R> 14/6+5
[1] 7.333333
R> 14/(6+5)
[1] 1.272727
R> 3^2
[1] 9
R> 2^3
[1] 8
R> sqrt(x=9)
[1] 3
R> sqrt(x=5.311)
[1] 2.304561

Scientific Calculator

R> f <- expression(x^2+3*x)    # you can check ?expression
R> D(f,'x')                    # Calculate (first) derivative of f 
                               # with respect to x

2 * x + 3

Class

• Data Structures
• Data Types

Data Structures (R-Objects)

• (Atomic) Vectos
• Matrices
• Array
• Data Frame
• List

Data Structures (R-Objects)

Data Structures (R-Objects)

• Homogeneous: Vector(1d), Matrix(2d), Array(nd)
• Heterogeneous: List(1d?), Data frame(2d)

Data Types

• Numeric (Double)
• Integer
• Complex
• Logical
• Character
• Special Values
• Date/Time

Variables are defined with different data types

Also

Variables are assigned with R-Objects

—> The data type of the R-object

Data Types - Numeric (Double)

Any number with (or without) a decimal point.

a <- 3.8
a
class(a)

b <- 4
b
class(b)

c <- sqrt(2)
c
class(c)

d <- 3.5:9.5
d
class(d)

class(1)

Data Types - Integer

Kind of a sub-class of the numeric class.

The suffix L tells R to store this as an integer.

a <- 7
a
class(a)

b <- 7L
b
class(b)

c <- 5:9
c
class(c)

d <- 5.1:9.1
d
class(d)

class(3.2L)

Numeric and Integer

pi

sqrt(2)^2-2

• Numeric (64-bit) -> big memery and calculations

• Integer (32-bit) -> Constant lalues like ID

• 6 digits after decimal

• 16 significant digits

Data Types - Complex

Complex: x2 = −1 (imaginary number)

a <- i

b <- 1i
b
class(b)

class(1+2i)
class(2iL)

try

class(((1i^2)^2))

is.complex((1i^2)^2)

isTRUE(is.complex((1i^2)^2))

(1i^2)^2

Data Types - Logical

TRUE or FALSE - Logical Operators

• < (less than)
• <= (less than or equal to)
• > (greater than)
• >= (greater than or equal to)
• == (exactly equal to)
• != (not equal to)
• !x (Not x)
• x | y (x OR y)
• x & y (x AND y)
• isTRUE(x) (test if X is TRUE)

Data Types - Logical

5 < 9
5 < -9
a <- 5 < -9
class(a)

1:10
1:10 >= 5
x <- 1:10 >= 5
1:10 < 2
y <- 1:10 < 2
x | y
z <- x | y
z
!z
class(z)

b <- 4:8
b
c <- 7:11
c
b != c
d <- 5:12
b != d

Data Types - Character

Data type consists of letters or words. String.

single quotes: ‘…’ or double quotes " … "

name <- emir

name <- 'emir'
name
class(name)

a <- 23
a
class(a)
b <- '23'
b
class(b)

print('hello')
cat('hello')
class(print('hello'))
class(cat("hello"))

Special Values

Null, Infinity, Not a Number, Not Available

NULL   # Null (“empty” entity)

Inf    # Infinity
class(Inf)
Inf*-9
is.finite(Inf)
1/0

NaN    # Not a Number
class(NaN)
-Inf+Inf
is.nan(5^(-Inf/Inf))
0/0

NA    # Not Available (“missing” entity)
class(NA)

Data Types - Date/Time

Sys.Date( ) 
date()

date <- "2007-06-22"
class(date)
date1 <- as.Date(date)    # Coercion
class(b) 

date2 <- as.Date("2004-02-13")
date1 - date2
date_difference <- date1 - date2
class(date_difference)

%d    day as a number (0-31)        01-31
%a    abbreviated weekday         Mon
%A    unabbreviated weekday       Monday
%m    month (00-12)               00-12
%b    abbreviated month           Jan
%B    unabbreviated month         January
%y    2-digit year                07
%Y    4-digit year                2007

today <- Sys.Date()
format(today, format="%B %d %Y")

Coercion

Coercion

3
class(3)
as.numeric(3)
as.character(3)
as.logical(3)
FALSE
class(FALSE)
as.character(FALSE)
as.numeric(FALSE)
as.numeric(TRUE)
TRUE+TRUE
class(TRUE+TRUE)

Data Structures

• Vector
• Array
• Matrix
• Data Frame
• List

(Atomic) Vector

The simplest data structure in R

Vectors are a list-like structure that contain items of the same data type.

spring_month <- "April"
spring_month
spring_months <- c("March", "April","May","June")
spring_months
class(spring_months)

c means “combine”

(Atomic) Vector

myvec <- c(1, 3, 1, 42)
a <- 35
myvec2 <- c(3L, 3.45, 1e+03, 64^0.5, 2+(3-1.1)/9.44, a)
myvec3 <- c(myvec, myvec2)
myvec3

x <- c("all", "b", "olive")

Length of a vector, length(vector_name)

length(x)

Indexing element, vector_name[element_position]

x[2]

Manipulating element of vector, assigning arrow

x[2] <- "b_new"
x

Note: In R, counting elements start position 1, not 0.

(Atomic) Vector

y <- c( 1.2, 5, "Rt", "2000", 20, 4905)
y [0]
class(y)
y

Sequences

7:16.4
a <- 7:16
a
seq(from=7,to=16,by=3)
seq(50,150,25)
seq(50,149,25)
seq(from=3,to=27,length.out=40)

Round

3/2
round(3/2)
round(5.1)
round(pi)

(Atomic) Vector

Repetition

rep(x=1, times=4)
rep(x=c(3, 62, 8),times=3)
rep(x=c(3, 62, 8),times=3,each=2)

Sorting

sort(x=c(2.5, -1, -10, 3.44))    # decreasing=FALSE (default)
sort(x=c(2.5, -1,- 10, 3.44), decreasing=TRUE)

Random - Uniform Distribution

runif(15, min = 20, max = 45)
runif(15, 20, 45)
runif(25, 60, 50)

Random variable can be saved

set.seed(1)
runif(15, 20, 45)

Matrices

Vectors indexed using two indices instead of one.

n <- runif(9,1,100)    
n
matrix(n, nrow = 3, ncol = 3)

n2 <- runif(10,1,100)    
matrix(n2, nrow = 3, ncol = 3)

Matrices

x <- as.numeric(seq(10,120,10))
mx <- matrix(x,3,4)                  # n, nrow, ncol
mx
class(mx)
class(mx[1])
typeof(mx)

mx[1,]
mx[,2]
mx[,2:4]
mx_new <- mx[,2:4]
mx
mx[2,3] <- "rose"
mx
class(mx)
typeof(mx)

mx_new <- as.numeric(mx)
mx_new
class(mx_new)
typeof(mx_new)

Matrices

m_mycol <- matrix(c(1, 2, 3, 4, 5, 6),
               nrow = 2,
               ncol = 3,
               byrow = FALSE)       # Default
m_mycol 

m_byrow <- matrix(c(1, 2, 3, 4, 5, 6),
               nrow = 2,
               ncol = 3,
               byrow = TRUE)     
m_byrow      
t(m_byrow)

length(mx)
dim(mx)

Arrays

x <- 1:24
x
array(x, dim = c(4,3,2))    # raw, col, level

arr <- array(x, c(4,3,2))
class(arr)
typeof(arr)

Arrays

arr <- array(data=10:33,dim=c(3,4,2))
arr
arr[2,2,1]
arr[-1,,]

Practice

Scientific Calculator

Practice

Scientific Calculator

Problem: Compute double, triple or higher order integrals

install.packages("cubature")
library(cubature)

f <- function(x) 1
adaptIntegrate(f,lowerLimit = c(0,0,0),upperLimit = c(4,4,4))

$integral
[1] XX

Practice

Create a Function

Problem: Take a sample belonged to population and sum

pop <- 1:6                    # This is my population
samp <- sample(pop, size = 2) # This is my sample, I choose two var.
sum(samp)

pop
samp

I want to create a new function named roll()

roll <- function() {
pop <- 1:6 
samp <- sample(die, size = 2) 
sum(samp)
}

roll()

Practice

Create a Function

Problem: What if we removed one line of code from our function and changed the name pop to box ?

roll2 <- function() {
samp <- sample(box, size = 2) 
sum(samp)
}

roll2()

Re-create function

roll2 <- function(box) {
samp <- sample(box, size = 2) 
sum(samp)
}

roll2(box = 1:4)
roll2(box = 1:6)
roll2(1:20)

Practice

Create a Function

• You can add new options
• { } and () are important

Practice

1. Print your name as a character string.
2. Print your age as a numeric type.
3. Print your age as a character type.

print()

4. Create a numeric vector with your favorite numbers.
5. Check the lenght of the vector, lenght().
6. Choose the last element (indexing) with [].
7. Create 4 × 2 matrice, fill with numbers
8. Delete first row.
9. Generate 48 random number and assign, runif().
10. Create and store a three-dimensional array with six layers of a 4 × 2 matrice, and fill it with these random numbers.

Summary

• Arithmetic Operators ( +, -, /, x )
• Logical Operators ( <, >, ==, != ….)
• Special Values ( NULL, Nan, NA, Inf)
• Vector, Matrice, Array (1d and Homogeneous)
• class(), print(), seq(), runif()
• c(), []
• ?xxx or help(xxx)
• install.packages(), library()

QUIZ

https://kahoot.it/

6th Week - R Language Part 2

List - Data Frame - Attributes - ATMOS

Homework

Udemy – Introduction to R, Section 3 (Video 22-25)

LINK

Quiz

List and Data Frame